Trichoniscoides sicoensis Reboleira & Taiti, 2015

Reboleira, Ana Sofia P. S., Gonçalves, Fernando, Oromí, Pedro & Taiti, Stefano, 2015, The cavernicolous Oniscidea (Crustacea: Isopoda) of Portugal, European Journal of Taxonomy 161, pp. 1-61 : 13-17

Trichoniscoides sicoensis Reboleira & Taiti sp. nov.

urn:lsid:zoobank.org:act:FCBE373B-42CE-4305-A932-28D88355FFB8

Figs 7 A–G, 8A–E, 9A–E

Diagnosis

A blind and colourless Trichoniscoides characterised by the male pereopod 7 merus having a lobe on the mid-sternal margin, the male pleopod 1 exopod having a broadly rounded outer margin and two unequal setae, the endopod having a fusiform distal article with a distinct circular suture in the middle, and the male pleopod 2 endopod having thickset distal article bearing two short triangular lobes and two setae at the apex.

Etymology

The new species is named after the Sicó karst area, where the species occurs.

Material examined

Holotype

PORTUGAL: ♂, Gruta da Cerâmica , Sicó Massif, 21 Mar. 2010 ( MZUF).

Paratypes

PORTUGAL: 10 ♂♂, 12 ♀♀, Gruta da Cerâmica, Sicó, 21 Mar. 2010 ( MZUF); 7 ♂♂, 11 ♀♀, same locality, 28 Nov. 2009 (SR); 4 ♂♂, 4 ♀♀, same locality, 10 Jun. 2011 ( ZMUC); 4 ♂♂, 5 ♀♀, same locality, 2 Mar. 2013 ( MZUF); 12 ♂♂, 8 ♀♀, Gruta da Senhora da Estrela, Sicó, 20 Nov. 2009 ( MZUF); 5 ♂♂, 12 ♀♀, same locality, 29 Aug. 2009 (SR); 3 ♂♂, same locality, 11 Jun. 2009 ( ZMUC); 1 ♂, Gruta do Soprador do Carvalho, Sicó, 12 Jun. 2011 (SR); 2 ♂♂, 3 ♀♀, same locality, 8 Jun. 2013 ( MZUF); 3 ♂♂, 2 ♀♀, Gruta do Algarinho, Sicó, 9 Jun. 2013 (SR); 3 ♂♂, 1 ♀, Gruta da Arrifana, Sicó, 12 Jan. 2013 ( ZMUC); 1 ♂, 2 ♀♀, Gruta de São Simão, Sicó, 30 Nov. 2013 ( MZUF).

Description

Maximum size: ♂ 3.5 × 1.2 mm; ♀ 3.9× 1.2 mm. Body colourless and slightly convex ( Fig. 7A ). Dorsum smooth, with scattered triangular scale-setae ( Fig. 7B ). Cephalon ( Fig. 7 C–D) with rounded frontal lateral lobes not protruding frontwards. Eyes absent. Pereonites 1–4 ( Fig. 7A ) with rounded posterior corners; pereonites 5–7 ( Fig. 7A ) with epimera pointing backwards. Pleon ( Fig. 7A, E ) narrower than pereon; pleonites 3–5 with small epimera and short posterior points. Telson ( Fig. 7E ) about three times as wide as long, with distal part trapezoidal with concave sides. Antennula ( Fig. 7F ) with three articles; third article with distinct spine and three long aesthetascs at apex. Antenna ( Fig. 7G ) with fifth article of peduncle shorter than flagellum; flagellum with five articles with two long aesthetascs on second article. Mandibles ( Fig. 8 A–B) with two penicils on the right and three on the left; molar process without penicils. Maxillula ( Fig. 8C ) with inner branch bearing three penicils at apex, inner one distinctly longer than other two; outer branch with 11 teeth and two thin stems. Maxilla ( Fig. 8D ) apically bilobed and setose, with outer lobe smaller than inner one; inner lobe with several long stout setae. Maxilliped ( Fig. 8E ) endite triangular, with stout triangular penicil at apex; palp distally rounded, long setae, and basal article with two short compound setae. Uropod ( Fig. 7E ) with exopod distinctly longer than endopod and more distally inserted; exopod with several long, pointed setae and endopod with a long and a short seta at apex.

MALE. Pereopods 1 ( Fig. 9A ) to 3 with an area of short quadrangular scales on sternal margin of carpus and merus. Pereopod 7 ( Fig. 9B ) merus with distinct cylindrical lobe, with short seta at apex on mid-sternal margin. Genital papilla ( Fig. 9C ) fusiform. Pleopod 1 ( Fig. 9D ) exopod as long as wide, with broadly rounded outer margin and two unequal setae on distal lobe; endopod with basal article quadrangular with convex inner margin and concave outer margin, distal article fusiform with distinct suture in middle and setose apex. Pleopod 2 ( Fig. 9E ) exopod trapezoidal with large seta at apex; endopod biarticulated, distal article about 1.5 times as long as basal one, thickset, with two short triangular lobes and setae at apex.

Remarks

This new species is tentatively included in the genus Trichoniscoides since it has all the characters of the genus, except for the distal article of the male pleopod 1 endopod, which shows a distinct circular suture in the middle, and the thickset distal part of the male pleopod 2 endopod. These characters are present also in an epigean species described by Gregory et al. (2012: 7, fig. 4) as “? Trichoniscoides species C” from Avión, valley of Río Valdeiras, Orense, north-western Spain, and Castanheira, Viana do Castelo, northern Portugal. The new species differs from the one recorded by Gregory et al. (2012) in the shape of the basal article of the male pleopod 1 endopod and of the distal part of the male pleopod 2 endopod. Trichoniscoides sicoensis Reboleira & Taiti sp. nov., together with the species recorded by Gregory et al. (2012), might belong to a distinct genus, but this can only be confirmed when other species with similar characters are found. For the presence of a lobe on the mid-sternal margin of the male pereopod 7 merus, the new species also resembles T. broteroi , from which it is distinguishable by the shape of the male pleopods 1 and 2. A hook-like lobe on the sternal margin of the male pereopod 7 merus is present also in the “aquitano-languedocien” group of species (sensu Vandel 1960 a), but in the species of this group the lobe is near the base instead of being on the mid-part of the sternal margin.

Ecological notes

This species seems to be endemic to caves of the Sicó karst area. In Gruta do Soprador do Carvalho one specimen was collected under a stone completely submerged in the cave stream. Despite the amphibian behaviour and submersion tolerance, this species is mostly found in the superficial parts of caves, where roots are abundant. Several troglobiotic species are known to share this habitat with T. sicoensis Reboleira &Taiti sp. nov.: the pseudoscorpions Roncocreagris blothroides (Beier, 1962) , R. borgesi Zaragoza & Reboleira, 2013 and R. cavernicola Vachon, 1946 ; the millipede Scutogona minor Enghoff & Reboleira, 2013 ; the woodlice T. broteroi , Miktoniscus longispina Reboleira & Taiti sp. nov. and Porcellio cavernicolus ; and the rove beetle Domene lusitanica Reboleira & Oromí, 2011 ( Reboleira et al. 2011 b, 2013 b; Enghoff & Reboleira 2013 a).

Figures

Fig. 7. Trichoniscoides sicoensis Reboleira & Taiti sp. nov. from Gruta da Cerâmica, Sicó. — Paratype, ♀. A. Specimen in dorsal view. — Paratype, ♂. B. Dorsal scale-seta. C. Cephalon in frontal view. D. Cephalon in dorsal view. E. Pleonites 4, 5, telson and right uropod. F. Antennula. G. Antenna.

Fig. 8. Trichoniscoides sicoensis Reboleira & Taiti sp. nov. from Gruta da Cerâmica, Sicó, paratype, ♂. A. Right mandible. B. Left mandible. C. Maxillula. D. Maxilla. E. Maxilliped.

Fig. 9. Trichoniscoides sicoensis Reboleira & Taiti sp. nov. from Gruta da Cerâmica, Sicó, paratype, ♂. A. Pereopod 1. B. Pereopod 7. C. Genital papilla. D. Pleopod 1. E. Pleopod 2.